Great work! This is an excellent take on the theme. I think others already mentioned, but the web version was almost unplayable for me due to lag (the download version played very smoothly). The juice in this game is amazing (the screenshake and freezeframe upon hitting the monster is excellent).
I know this is just me being bad, but it felt like most of my deaths were due to clicking a little to early (while the bullet was red). It would be awesome if there was a sound effect that played as soon as the bullet turns from red to black, just to make it a little easier to time your mouse clicks.
Awesome job! Again, this is a really cool take on the theme.